we're going to take you on a fascinating and emotional journey tonight, with some of the youngest victims of America's obesity crisis. We're going off to camp with two children. The first stop is not the pool or the craft tent. It is a weigh-in. The goal here is to lose up to 35 pounds in just weeks. So, can these kids make it? Here's my "Nightline" co-anchor, juju Chang. Reporter: It's part of the annual rite of passage for thousands of kids. Leaving home for summer camp. But for 12-year-old Brian and 11-year-old Audrey, it's not just a season of fun in the sun. They're hoping for a fairly radical transformation. Inside and out. I want to be healthy again. Reporter: Audrey and Brian are joining 600 other kids at camp Shane, in ferndale, New York. I'm superexcited to go. Reporter: On Long Island, Brian and his mother, Carol, are finishing packing up a Summers' worth of belongings. The six weeks at camp will be the longest this seventh grader has been away from home. I'm nervous about missing my parents and my little sister. Brian is very lazy. He likes to sit in front of the computer. But when it comes to exercising, he lacks in that expect. Reporter: The night before he sets off, they visit Brian's favorite restaurant. I'll have the veal Marsala. Pasta. Reporter: Friends and family helping celebrate with, what else? Food. In New York City, Audrey and her mother, Miranda, enjoy one last feast. I want her to get her body to a place that feels so good, that she doesn't want it to be any other way. Reporter: For Brian and Audrey, they're pinning their hopes on weight loss camp. And on this day, it's time to say good-bye. Getting picked up to go to camp Shane. He's leaving me for six weeks. I'll send you letters. Reporter: Saying good-bye is easier said than done. I'm good. I'll miss you. Reporter: The camp's motto is way better than a fat camp. They claim the dieters lose 30 to 35 pounds in 9 weeks. Audrey and Brian are one in the every three children considered overweight or obese. It's a three-hour road trip to ferndale, New York. Your waist. And then your hips. Reporter: First stop, the weigh-in. Brian checks in at 225 pounds. When I was being measured, I felt a little embarrassed at my own size, physically. Reporter: Audrey weighs 114 pounds. At age 11, she hits the 98th percentile in weight for her height. For years, her pediatrician suggested she slim down. Knowing my exact weight makes me want to work harder. And it makes me happier to know that I'm going to be helping myself. Reporter: Over the next six weeks their priority is to lose that weight. Break old habits and hopefully create new, healthier ones. You can call it the four "E." Eating, exercise, education, and emotion. We check in with Brian after spending two weeks at the camp. What makes you sad in your life outside of this camp? I guess being bullied at school. Reporter: What happens? People make fun of me, like left and right. I couldn't turn a corner in the hallway without being made fun of? Reporter: So you ate to make yourself feel better? Yeah. Reporter: A few cabins over, Audrey says the group sessions are uncovering her booby traps. My parents got divorced. And then, they skyrocketed. I started eating adult-sized portion. At restaurants, I would finish the whole plate. Reporter: But the camp staff says the new habits they learn at camp can only turn into a lifetime of change is there is change at home. We ask parents not to eat out so much. The portions are too big. And there's too many calories. Reporter: And even on a field trip to New York City, Audrey stays true to her new diet, eating healthy, despite temptations from this restaurant's menu. I'm not craving anything unhealthy right now. Reporter: Back at camp Shane, Brian, veering off course. I heard on visiting day, you want to go home, bad? Definitely. Reporter: But Brian rallies. And he recommits to staying for the duration. Do you feel confident you can finish it out? Definitely. I feel pretty confident. Reporter: He is sounding confident. But one week after our visit, on day 21. I miss my mom too much. Reporter: Brian leaves the program midway through the six-way stint. He's going home with some results. Brian was able to lose 14 pounds and nine inches off his waist. I didn't think it would be that much exercise. Reporter: But it wasn't just the athletics Brian disliked. He said he wasn't happy socially, either. I didn't have many friends at camp. Reporter: Brian's mother says she supports her son 100%. Brian left camp Shane because he was having a horrible time. Reporter: Back at camp, Audrey sticks it out. And spend three weeks. Last summer, I would never have gotten up this hill. Reporter: Swimming. And taking Zumba classes. The pounds and the insecurity seem to be melting away. I feel beautiful. Reporter: It's the camp's final day. And time for another emotional departure. Six weeks, I'm happy with my weight. I'm really not confident. And now, I'm really confident. And I'm real excited. Reporter: After six, long weeks, Audrey's mom is blown away. I'm 102 pounds. Great job, babe. There's a comfort level in her body I haven't seen before. There is nothing left of you. I'm happier. More confident and more open. Reporte Reporter: I love what they did. It's so cool. Audrey goes for a bold, new look. I like red on top. And I have pink to match it. Reporter: Audrey got the makeover she was hoping for. But she's wise enough to know, this isn't the end. It's just the beginning. It does take some time. You can decide you want to make the change in five minutes that it can take. It can take five weeks to achieve your goal. Reporter: For "Nightline," I'm juju Chang, in New York.

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Mother Apologies on Facebook for Children's Real-Life Behavior

Now Playing: GNC to Toughen Supplement Testing Procedures

Now Playing: Angelina Jolie Makes Her 1st Post-Surgery Appearance

Now Playing: How Much Time Should Parents Spend With Their Children?

Now Playing: Instant Index: Coffee Study Reveals a Cup a Day Could Decrease Risk of Liver Cancer

Now Playing: Parents Grow Angry Over BMI Tests at School

Now Playing: School Tells 'Tiny' Girl Her Body Mass Index Is Too High

Now Playing: Upscale Toothpaste Claims to Repel Plaque

Now Playing: Why People Are Wearing Yellow Today

Now Playing: Hawaii Woman Receives Bionic Eye Implant

Now Playing: Pit Bull Adores Her Adopted Newborn Kitten

Now Playing: Senate Special Committee on Aging: Finding an Alzheimer's Cure

Now Playing: Acroyoga Could Strengthen Your Body and Relationship

Now Playing: Angelina Jolie Takes Fight to Cancer

Now Playing: Ken Burns, Katie Couric Take on Cancer in New Documentary

Now Playing: {{itm.title}}

{"id":25171786,"title":"Kids Aiming to Lose Weight Take on Summer Camp ","duration":"7:08","description":"Young campers hope to have fun while shedding pounds at Camp Shane, which tackles weight loss, dieting and emotional triggers for overeating.","url":"/Nightline/video/nightline-kids-aiming-lose-weight-summer-camp-25171786","section":"Nightline","mediaType":"Default"}